* Introduce hasSession field in datasource
That makes isLogged more consistent as it will be '1' only when the player is online.
* Fixes
* Fix unit testing
* Update config doc
* Create SessionService
* Create test for SessionService, avoid DB operations if sessions are disabled
* Cleanup: remove outdated warning for session timeout = 0
- Remove outdated warning
- Encapsulate session enabled check in SessionService
* Fix failing SessionServiceTest, add data source integration tests for session methods